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Date: Tue, 31 Oct 2023 22:56:22 +0700
Message-ID: <CAEZPtU6WPwo77sGObYnX78EqvYLjohhAk3eQ31eJoSwV1+hdBA@mail.gmail.com>
To: tag Knife <fenniclog@gmail.com>
Cc: "Su, Tao" <tao.su@intel.com>, PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Make PHP JIT to generate AVX2/AVX3 for performance improvement?
From: pierre.php@gmail.com (Pierre Joye)

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On Tue, Oct 31, 2023, 3:57 PM tag Knife <fenniclog@gmail.com> wrote:

> > Hi  Guys,
> >
> > A quick question: is it possible to enable AVX2/AVX3 in PHP JIT generated
> > code, and hence can get some performance improvement?
> > Just check the community first: if anyone has already tried that or got
> > some experiences? before we dive into this investigation.
> > We are discussing if we could get some extra performance via new AVX
> > instructions in PHP program execution.
> >
> > Thanks.
> >
>
> AVX3 might be too new to just flat out generate for it. But
> It can be quite simple for the JIT compiler to be aware of what
> features flags are enabled on a CPU and generate compatible
> instructions that will run on that CPU.
>

it is not really new, however the gain for most cases are not necessarily
significant but for specific cases.

For most usages in php, at a request level, the gain will be barely
measurable.

Also for latest avx, most hosting servers won't have them anyway.

I would think some specific APIs to prepare specific data to be processed
using the best available runtime intrinsics would bring much more than in
JIT.

As a sidenote, most libraries used by php,  where larger intrinsics vectors
bring something, implement them already.


best,
Pierre

>

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